Evidence indicates that rat liver nonhistone chromosomal proteins (NHC-proteins) select a group of DNA sequences via rat DNA binding interactions. Our proposed research is to isolate these binding components based on their theoretical binding characteristics. A protein can bind to a specific operator site and nonspecific sites. The two interactions can be differentiated based on the strong operator site dissociation-constant. Employing a purified fraction of rat liver NCH-proteins, DNA-proteins will be determined. Rat DNA enriched with sites can identify those proteins which can fractionate the rat genome into high affinity DNA binding sites. With protein components defined, the functional significance can be questioned. The possibilities are structural involvement with histones or genetic involvement with RNA polymerase. Effect on the secondary interactions of the DNA sequence can be investigated by thermal DNA denaturation, affinity toward superhelical DNA, or in vitro RNA polymerase assay. BIBLIOGRAPHIC REFERENCE: High Affinity DNA Binding NHC-Proteins in Rat Liver Chromosomes, L. Jagodzinski, J.C. Chilton, J.S. Sevall, Biophysical Journal, 16 F-PM-Ec, Feb., 1976.